CANARIES IN A COAL MINE

Canaries were used in mines as early warning systems to detect dangerous gases, such as carbon monoxide. Miners took caged canaries into the tunnels with them. If the gas in a mine reached a level where it impacted the canary, the miners knew they were at risk, too, and would attempt to leave. Top fact: The canaries usually revived. We know someone who has an RV trailer at a permanent camp site. Each year, when she closes the trailer for the winter, she places a few peanuts in strategic locations. In the spring, when she returns to open the trailer, if the peanuts are gone, she knows there were rodents in the trailer—another handy early warning system, triggering a whole other level of cleaning.